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Best Backpacking Water Filter: Steripen Adventurer Review

Use: The best backpacking water filter for camping and hiking

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Price reflects
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Lightweight The batteries
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Purifies at the
click of a button

Review: What I like

  • Seriously fast UV water filter when compared with other options on the market
  • Uses UV light to eliminate practically all viruses and bacteria from water
  • Both small and lightweight, making it the ideal water purifier for camping, hiking or backpacking

Review: What I don’t like

  • It doesn’t work with water containing visible particles
  • The batteries and type of bottle needed for this Steripen are very specific and can be difficult to buy when travelling
  • It’s more expensive than other backpacking water filters
Image of the steripen adventurer, the best backpacking water filter steripen reviews


If you’re looking for a quick and easy way of reducing your reliance on plastic bottles when you travel, or want to find a dependable uv water filter for backpacking, hiking or camping, the Steripen Adventurer Opti* is for you. 

*Since I had my Steripen Adventurer, many outdoor shops are no longer stocking it and instead have the Steripen Ultra UV Water Purifier. I would also recommend this Steripen, so I have also included links to this product.

How I used the Steripen Adventurer Opti

Cutting down my environmental impact

When was the last time you bought bottled water? If you’re at home, perhaps not so recently. But what about the last time you were travelling?

We’ve all been there, uncertain about whether the tap water is indeed safe to drink and concerned for the inevitable Deli Belly is if turns out that it’s not. The answer? Buying bottled water – it’s a less risky strategy after all.

I personally don’t want to consider the number of plastic bottles of water that I went through per day before I invested in a water filter. A million plastic bottles are bought per minute around the world, a horrifying statistic that really highlights the impact that buying water when we travel can have.

Not only this, but buying bottled water is hardly a cost-effective way of travelling. When I first moved to Bolivia, I was spending at least 50p (60 cents) daily on water, a cost that really adds up when you’re backpacking longer-term. If I’d have continued with that sort of spending for an entire year, I could easily have paid over £180 ($240 USD).

Finding a reliable – and fast – portable water filtration system

About three months into my trip, I was so disgusted with my environmental impact and the amount of money I was wasting daily that I finally bought a water filter. It wasn’t actually the Steripen Adventurer Opti; my brother brought me the Sawyer Mini water filter (buy it on REI | Amazon).

It came with a 0.5 litre (16oz) pouch and a filter attachment through which you squeeze the water by gently folding the plastic pouch. It worked perfectly – when my brother did it.

When I used it? Well, I didn’t have quite the same amount of patience and the bag split close to the filter (apparently this is a common issue if you’re a bit heavy-handed with it). It also felt like it took a long time to filter (a couple of minutes – but hey, I’m impatient!).

I was not 100% convinced my brother brought me the Sawyer Mini water filter (buy it on REI | Amazon), so I did some research and came across the Steripen Adventurer Opti. It was definitely more of an investment due to its higher cost, but one that I know has paid for itself many times over due to its versatility of use, portability and speed of purification.

Read my article about the best backpacking water filters and purifiers to find out more about why I prefer the Steripen Adventurer Opti over the competition.

photo of the Steripen Adventure Opti in this best backpacking water filter steripen review
The Steripen Adventurer comes with a padded case and instruction manual

Is the Steripen Adventurer Opti water filter for you?

The Steripen Adventurer Opti has been an excellent purchase for me as it suits my style of travel. I regularly visit countries and cities where tap water isn’t safe to drink (or no one is quite sure) and I don’t want to take the risk.

When I bought this Steripen, I was also looking for a portable water purification system, something fast and lightweight that would function as a backpacking water filter, both day-to-day as I’m travelling but also on the trail, where it would quickly – and easily – purifier water.

The thing is, if you’re planning on hiking somewhere where access to clean-looking water may be an issue, the Steripen Adventurer is definitely not for you. In the instruction manual, it recommends that the Steripen Adventurer is only effective for treating up to water that is “as cloudy as weak lemonade” and which require double treatment to ensure the water is safe.

Beyond this, where there are visible floating objects or the water is significantly less clear, the UV light that purifies the water cannot function 100%, leaving you open to ingesting nasty things in the water.

This has only been an issue once when I’ve been hiking. After heavy rain in Torres del Paine National Park, the water pump at Campamento Serón wasn’t working and the water we took from the river had a large amount of sediment in it. Unfortunately, the Steripen Adventurer just wasn’t up to the job.

Two German guys on the campsite had the Sawyer Gravity Water Filter which you basically hang from a tree and let gravity push the water from one bag through the water filter and into the second bag) while the Sawyer Mini water filter (buy it on REI | Amazon) (which my dad has since assured me works excellently for filtering water taken directly from muddy puddles) would have been perfect in the situation too.

A final alternative to investing in one of these hiking or backpacking water filters is to rely on boiling water, the cheapest method. It’s fairly fail safe, but one I’ve personally found time consuming, particularly when you have to boil water for longer periods of time at altitude and then you’ve got to wait for the water to cool. It can often leave the water with a slightly metallic taste.

best backpacking water filter steripen reviews
It’s quick and easy to purify water; just make sure you’ve got a bottle with a big enough opening!

Full Specification

Weight: 70g (2.5oz) without batteries
Filter type: Ultraviolet light
Kills:​ 99.9% of protozoa, 99.99% of viruses and 99.9999% of bacteria
Speed: Purifies 0.5l (16oz) in 48 seconds; 1l (34oz) in 90 seconds
Number of
Can run 50 treatments per set of batteries
Battery type:​CR123A
Recommendations: Must be used with a bottle with 4.4cm (1.75in) diameter such as a wide-mouth Nalgene bottle (also available on REI)

Steripen Adventurer Opti Review

I’ve been using the Steripen Adventurer Opti without issue for several years now. During those times, I’ve been particularly impressed with the following:

The Positives

Speed and ease of use

  • It’s the most straightforward filter I’ve used. Take the plastic lid off the UV bulb, submerge it in your water bottle, press the button (once to treat one litre, twice for 0.5 litres) and stir to ensure that purification is even. The UV bulb will start emitting light; continue stirring until this goes out and the light beneath the button begins to flash green to indicate success.
  • If there’s a problem, the button will flash red, with the exact issue indicated by the pattern of flashes (something deciphered in the instruction leaflet that comes with the Steripen – so be sure to keep it with your Steripen when you’re travelling!).
  • It takes either 48 seconds for 0.5 litres or 90 seconds for one litre – a seriously fast time in comparison with other water filters.

Weight and size

  • At only 103g (3.6oz) with batteries and 15.5cm (6in) in length, it’s small enough to to slip into your pocket or your day pack to be used when hiking or when sightseeing in town for filtering tap water, making it the best backpacking water filter in my book.


  • Unlike the Sawyer Mini where the bag split from excess pressure (and my impatience), I can’t think of many ways that you could actually break the Steripen Adventurer. The UV bulb is delicate, but as long as you keep the plastic case on it when it’s not in use and stored in its padded, protective bag, there should be no reason why it gets damaged. Let’s face it: I’m hugely disaster prone and mine is still in one piece!
  • The batteries also last for ages. The official claim is that they can manage 50 treatments before needing to be replaced, but I’m sure mine have been going for longer.

I’d be lying in this Steripen Adventurer review if I was to say that this product is 100% perfect and there are a number of areas that are worth considering before you invest.

However, in the four and a half years that I’ve been using this backpacking water filter, the problems have genuinely never been enough to make me regret buying this Steripen.

best backpacking water filter steripen reviews

Things to Consider

Ease of use

  • The biggest problem I’ve faced with the Steripen Adventurer is the fact that any old bottle won’t work with this water filter. You need one with an opening of 4.4cm (1.75in) for the Steripen to fit inside. To be fair, this isn’t a huge issue; you just need to make sure that you buy a reusable water container (such as this one) before you leave for travelling and try not to lose it along the way (which I’ve done) – although it’s fairly standard to find bottles with larger mouths now anyway, so you can easily replace it on the road.
  • The batteries are also a weird size (CR123A). You can buy them on Amazon, but they tend to come in large quantities. I’ve ended up buying a box to ensure that I always have spares available when required.


  • The Steripen Adventurer isn’t the cheapest backpacking water filter – that accolade easily goes to the Sawyer Mini water filter (buy it on REI | Amazon). However, I genuinely think that it’s the most cost – and time – effective backpacking water filter that you can find. I’ve since tried out the Grayl Geopress water filter (Buy it on REI|Amazon), which I did find useful and quite fast to use, but it’s also much bigger (and heavier!).
  • Although it is a real investment, the Steripen Adventurer has been an excellent water filter for backpacking and more than paid for itself over the past two years and I’m still very happy with purchasing it. Ultimately, it depends on your budget and how much time you want to spend filtering water.


  • As I’ve indicated, it doesn’t work with visibly dirty water so it’s the ideal solution for those looking for a hiking water filter where you’re likely to be using puddles or still water sources. If this is your intended use, I suggest you look at the Sawyer Gravity Water Filter or the Grayl Geopress instead.


The Steripen Adventurer Opti (buy it on Amazon or get the newer Steripen Ultra UV Water Purifier on REI) is a reliable, fast and easy to use backpacking water filter, giving you access to safe drinking water in a matter of minutes and helps you to completely avoid relying on environmentally damaging plastic bottles.

It’s almost at the top of its price point; the cheaper but more time-consuming and more breakable Sawyer Mini water filter (buy it on REI | Amazon) is an alternative, while for more hardcore camping or hiking adventures, the Sawyer Gravity Water Filter is the best alternative.

The Grayl Geopress (buy it on REI|Amazon) is a heavy but reliable option, too.

However, the Steripen Adventurer Opti’s ease of use and the fact that it’s not let me down in the past two and a half years of travelling, make it a real winner in my book!

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Read this expert review of the Steripen Adventurer, a portable water purifier ideal for backpacking, hiking and camping and other situations where you need safe, drinkable water fast. #waterfiltercamping #sawyer #steripen #bestwaterpurifier


Sunday 18th of July 2021

It's not a filter, it's a 'purifier'. In less developed countries tap water contains a lot of particles (rust first of all) this 'filter' would not remove. And you are consuming them all. Good luck with that. This is definitely paid unfair advertisement.

Steph Dyson

Thursday 25th of November 2021

Hi Alex, nope, it's my honest appraisal of a product I've used for seven years and counting. I've also not yet died from rust consumption but take your point on that one! Steph


Thursday 10th of September 2020

Have have one that is USB rechargeable. When I went to Everest Base camp my USB rechargeable one worked pretty well in the cold, my friend who had a AA battery one found that theirs didn't work when it was cold

Steph Dyson

Saturday 21st of November 2020

Thanks Crystel, that's a really useful piece of advice! Steph